[Zope3-dev] Correctly sending ObjectModifiedEvents [was SVN: zope.webdav/trunk/src/zope/webdav/ Emit an ObjectModifiedEvent on successfully modifying a property with]

[Philipp von Weitershausen]

Michael Kerrin wrote:
> Log message for revision 72694:
>   Emit an ObjectModifiedEvent on successfully modifying a property with 
>   the proppatch method.

...
>  
> +        if changed:
> +            zope.event.notify(ObjectModifiedEvent(self.context))
> +

Just emitting an ObjectModifiedEvent like that is pretty useless, IMO. 
With this you have no clue

- whether the object or the object's annotations were modified

- which properties of which schema were modified.

The good news is that the ObjectModifiedEvent API actually supports this 
kind of stuff, you just need to use it:

   info = Attributes(ITheSchema, 'foo', 'bar', 'blergh')
   notify(ObjectModifiedEvent(obj, info))

(Attributes is importable from zope.lifecycleevent). Note that the 
object must not necessarily provide ITheSchema, it could also be that 
the ITheSchema(obj) adapter was changed (this is useful when sending 
modified events for annotation adapters like IZopeDublinCore).

Unfortunately, not many places in Zope 3 itself are good examples of 
this. In fact, not even formlib sends this extra information along with 
the events, something I've been meaning to report and fix. (Thanks for 
reminding me to do so :)).

Philipp


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